Author Topic: Curing transformer hum by use of methylated spirits/shellac?  (Read 7571 times)

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Offline johansen

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Re: Curing transformer hum by use of methylated spirits/shellac?
« Reply #25 on: December 26, 2016, 06:30:32 am »
So, was scanning the old posts on sorensen power supplies and found this old post by tekfan in a 2011 thread about the same power supply as I have, which describes preregulation.

Edit: reading the theory of operation in an online PDF of the 2001 version of the manual (missing schematics) it doesn't mention pre-regulation as far as I can tell.


the preregistration discussed there is using an SCR as a switch (like in a buck converter).. and you need an inductor for energy storage. its going to make a lot more noise than a transformer and such systems should be easily identified compared to traditional linear power supplies. for example, the pre regulator and the linear regulator should be mechanically and electrically isolated from each other, and a large inductor, approximately the size of the main supply transformer is required. wouldn't supprise me if you find two additional transformers to provide power for the control circuitry, one for the pre regulator and one for the linear regulator.
« Last Edit: December 26, 2016, 06:33:16 am by johansen »

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